— B44 Buln American Museum of Natural History. [Vol. XXXIV, 
much among themselves as they do from the topotype of P. vortmani 
from which species I cannot distinguish them. The measurements of the 
molar series are: No..4300 =.25./7, 4892 = 25:., and 4393 = 25.7 mm., 
as compared with 25 mm. in the topotype of P. vortmanz. | 
Phenacodus copei sp. nov. 
Phenacodus vortmant Corr, Tert. Vert. 1885, p. 464, pll. xxixe, xxixf, Iviih, 
fig. 17 (not P. vorimani Cope, 1881); ‘“Trispondylus”’ vorimani, 1884, Am. Nat. 
(foot-note) p. 900 (not P. vortmani Cope, 1881). 
Type, Amer. Mus. Cope Coll. No. 4378, a nearly complete skeleton; 
Gray Bull beds, Bighorn basin, Wyo. J. L. Wortman, 1881. 
The discovery of excellent supplementary material of P. vortmani 
in the Lost Cabin beds serves to bring out differences between that species 
and the Gray Bull skeleton which Cope referred to P. vortmani. The differ- 
ences are of specific value, and the distinguishing characters are: p3-m3 = 
45 mm., mem; = 28 mm., p’-m° =3/, m'* = 23+ metacontiles reduced 
or absent; p® with tritocone very small, deuterocone with a posterior posi- 
tion, opposite the tritocone; ps without anterior basal cusp and with low 
posterior basal cusp; teeth more robust than in P. vortmanz. | 
In the type of P. coper the last lower molar is not reduced while the last 
upper molar is very much so. In a referred specimen (No. 15333) the lower 
molar is the same as in the type but the upper molar is not much reduced. 
The relative size of this tooth appears to be of little value as a specific char- 
acter in this genus. 
Occurrence. Kleven specimens, chiefly lower jaw fragments, from the 
Gray Bull beds are referred to this species. From the Lysite there are 
twenty-five specimens, mostly very fragmentary, and of these only two are 
from the typical Lysite, the balance being from Buffalo basin where this 
species is the only one of the genus represented. From the lower horizon of 
New Mexico two specimens are referable. 
From the Sand Coulee beds a single specimen (No. 16125) shows in the 
third upper premolar the characters of P. copei and in the lower those of 
P. vortmant, with which it also agrees in size of teeth. 
Phenacodus brachypternus Cope, 1882. 
Paleont. Bull., No. 34, 1882, p. 180; 1885, Tert. Vert., p. 433, pl. xxve, fig. 14. 
Type, Amer. Mus. Cope Coll. No. 4396, a left ramus with ps-m3; Gray 
Bull beds, Bighorn basin, Wyo. J. L. Wortman, 1881. 
